1. Field of the Invention
The present invention relates to a photographing apparatus which is adapted to move an imaging optical system or a lens barrel for guiding light from a subject, and which is preferable for use in a digital camera.
2. Description of the Prior Art
Recently, a photographing apparatus carrying out an electronic control such as a digital camera and a digital still camera has a high function and a multifunction. A control section in the photographing apparatus may execute a complicated control owing to the high function and multifunction. For achieving the complicated control there is manufactured a photographing apparatus in which an OS or operating system for an assembled instrument is mounted and a control section therein executes such a complicated operation.
Usually, several hundreds of m-sec are required for initialization of an OS or operating system and a relatively long period of time is required for starting of the OS. Such high function/multifunction cause an increase of the number of devices such as memories, objects of the initialization, so that the time required for such initialization is likely to be lengthened. A photographing apparatus carrying an OS thus suffers disadvantageously from a longer starting time until the apparatus becomes actually useable after a power supply is turned on.
In a photographing apparatus, in which a mechanical movement is executed such that a lens barrel is drawn out from a settled state being an accommodated state after the OS is initialized and the control proceeds to a photographing standby state, the initialization must be performed prior to the lens barrel being drawn out, so that the starting time is further lengthened.
The lens barrel includes a lens disposed therein and constituting the imaging optical system.
To solve the difficulty, Japanese Patent Laid-Open No. 2000-209485, for example, discloses that in addition to a main control section for controlling the whole of an apparatus by executing an OS there is mounted a sub control section for executing in parallel drawing-out of a power supply, a zoom, a lens barrel, etc., in the course of the starting of the main control section, whereby there is a reduction in the starting time since a power supply button is turned on.
When the main control section and the sub control section share their role, in view of the effect of a development work, it is desirable for improving the efficiency of the development of a product to share the works into a high function, a high-speed control function, and a simple work function.
The reason is that the debugging of software and the construction of a program can be concentratedly executed for the one control section, and a CPU containing an inexpensive mask ROM is employed for the other control section to reduce the manufacturing cost.
Particularly, in recent years a high magnification for an optical system of a camera is required, while the miniaturization of a camera is required together with the improvement of control accuracy required, so that the use of an expensive CPU for both control sections disadvantageously brings about a too expensive product in itself.
More specifically, owing to the miniaturization of a photographing apparatus, accuracy required for position control in drawing out a lens barrel has been increased. For realizing such higher position control accuracy, an expensive CPU with a high processing capability should be employed for the main control section. Use of an expensive CPU causes a significant rise of the manufacturing cost, resulting in a prior art photographing apparatus with the significant higher manufacturing cost.
Particularly, in a photographing apparatus which should execute initialization of a lens barrel, there are particularly required the reduction of a burden exerted on the development cost, an improvement of position control accuracy for a lens barrel, and the shortening of the starting time.
Additionally, it is common that the control section suffers from a relatively large electric power consumption. Because of this, a prior art apparatus including two control sections thereon is likely to have shortened operable time, compared with a photographing apparatus including only one control section, in a case where a battery having the same charging capacity is used in those apparatuses. It is therefore required to suppress overall consumed electric power and lengthen the foregoing operable time.